MarkerObjectODE2Coordinates

A Marker attached to all coordinates of an object (currently only body is possible), e.g. to apply special constraints or loads on all coordinates. The measured coordinates INCLUDE reference + current coordinates.

Interface

Provides: Coordinates
Connectors, constraints and loads that can use it: ObjectConnectorCoordinateVector

Parameters

The parameters of the item; in a dictionary, its type is ‘ObjectODE2Coordinates’:

name	type	default	description
name	String	‘’	marker’s unique name
objectNumber	ObjectIndex	invalid (-1)	body number to which marker is attached to
visualization	VMarkerObjectODE2Coordinates		parameters for visualization of item

Visualization parameters

VMarkerObjectODE2Coordinates has no parameters.

Drawing

The item draws nothing.

Detailed description

Marker quantities

quantity	symbol	as computed
coordinates	\(\cv = \qv\cRef + \qv\)	all ODE2 coordinates of the body, node after node in the order of its nodes, including their reference values
their velocities	\(\dot\cv\)	the time derivatives

Jacobians

The unit matrix of the size of the body’s coordinates. On a body without coordinates (ground) the values and the Jacobian are empty.

Mini example

#all coordinates of an object, here of a ObjectGenericODE2 with two free coordinates, tied by a
#coordinate vector constraint X1 q - X0 q_ground = offset, which is q0 - q1 = 0
node = mbs.AddNode(NodeGenericODE2(numberOfODE2Coordinates=2, referenceCoordinates=[0,0],
                                   initialCoordinates=[0,0], initialCoordinates_t=[0,0]))
oGeneric = mbs.AddObject(ObjectGenericODE2(nodeNumbers=[node], massMatrix=np.eye(2)))
mAll = mbs.AddMarker(MarkerObjectODE2Coordinates(objectNumber=oGeneric))
mNone = mbs.AddMarker(MarkerNodeCoordinates(nodeNumber=nGround)) #the ground node has no coordinates
mbs.AddObject(ObjectConnectorCoordinateVector(markerNumbers=[mNone, mAll], scalingMarker0=np.zeros((1,0)),
                                             scalingMarker1=[[1,-1]], offset=[0]))
mbs.AddLoad(LoadCoordinate(markerNumber=mbs.AddMarker(MarkerNodeCoordinate(nodeNumber=node, coordinate=0)), load=2))

mbs.Assemble()
mbs.SolveDynamic()

#both coordinates move together: a = F/2 = 1, q1 = a/2*t^2 at t=1
exu.sys['testResult'] = mbs.GetNodeOutput(node, exu.OutputVariableType.Coordinates)[1] #0.5

Relevant Examples (Ex) and TestModels (TM) with weblink to github: coordinateVectorConstraintGenericODE2.py (TM)